Amusement devices wherein a circular disc or ball is projected into a playing field are well known in the art. Pinball machines and the like have spring operated launch mechanisms for injecting a ball into a playing field. A user of such a device can vary the speed of a ball by varying the compression applied to the spring of a launching mechanism. Although such mechanisms permit a player to vary the speed of the ball, they do not permit the player to observe the speed of the ball in motion, and adjust the speed prior to injecting it into the playing field.